On Thu, 13 December 2001, "Walden H. Leverich" wrote:

> As I understand it CA Express has a dynamic port mapping scheme. There is
> one port (8477?) that is static and the job of that port is to hand out the
> ports for the other connections. So when telnet wants to connect it connects
> to 8477 and says "What's the telnet port?" The answer is (usually) 23 and
> then telnet connects to port 23.

I suspect you're referring to the server mapper (as-svrmap tcp) service that 
normally runs on port 449; port 8477 would normally have the as-netdrive 

Essentially, you connect to port 449 and send in a name from the service table 
such as "telnet" or "ddm" (case-sensitive and ASCII) and it returns a 32-bit 
binary port number for that service. To see it in action, just set up a comm 
trace and watch any PC connect. I have no idea how the same is handled on other 
platforms; it'd sure make a nice standard.

> Is there a way to add new things into that process? I have pc processes that
> need to connect to the AS/400, can I use this port-mapping routine for my
> own use too? I'd rather be flexible rather than hard-code the ports.

You can add entries to the system service table by using the Add Service Table 
Entry (ADDSRVTBLE) command. Really pretty simple once you've done it a couple 
times and works well. I use it to register my own sockets applications for 
AS/400 networks -- just have to remember to use QDCXLATE or some other means to 
make sure I'm talking ASCII. You might also consider using the Add TCP/IP Port 
Restriction (ADDTCPPORT) command to keep your chosen ports from being used by 
OS/400 for other purposes, and, of course, choose port numbers that will play 
nice with others.

Tom Liotta

Tom Liotta
The PowerTech Group, Inc.
19426 68th Avenue South
Kent, WA 98032
Phone  253-872-7788
Fax  253-872-7904

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